Injection catheter

ABSTRACT

An injection catheter is provided. The catheter comprises a catheter body comprising a flexible tubing having proximal and distal ends and at least one lumen therethrough. A tip section comprising a flexible tubing is mounted at the distal end of the catheter body. The tip section has a needle passage extending therethough. The needle passage has a proximal region having a proximal diameter and a distal region having a distal diameter less than the proximal diameter. A needle control handle is provided at the proximal end of the catheter body. An injection needle extends through the tip section, catheter body, and needle control handle and has a proximal end attached to the needle control handle and a distal end within the needle passage. The injection needle is longitudinally slidable so that its distal end can extend beyond the distal end of the tip section upon suitable manipulation of the needle control handle.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent applicationSer. No. 09/563,769 filed on May 1, 2000, which is acontinuation-in-part of U.S. patent application Ser. No. 09/280,202filed on Mar. 29, 1999, now U.S. Pat. No. 6,165,164.

FIELD OF THE INVENTION

[0002] This invention relates to a catheter for infusing therapeutic ordiagnostic agents into the tissue of organs, and more particularly to acatheter having a mechanism for controlled extension of an injectionneedle.

BACKGROUND OF THE INVENTION

[0003] Targeted delivery of therapeutic or diagnostic agents, such asoccurs in gene therapy, is very desirable but often presents a difficultchallenge. A potential benefit of targeted delivery is that there is anincreased efficiency obtained by the precise placement of thetherapeutic agent. There are several problems to his procedure whichmust be overcome in order to obtain satisfactory results from suchtherapy, such as the problems of obtaining access to the delivery site,transporting the therapeutic agent to the desired site, injecting thetherapeutic agent at the proper depth within the organ tissue, steeringthe distal end of the catheter to a desired location within the organprior to infusing the agent, and positioning the distal tip of thecatheter at precisely the same location where prior measurements haveindicated that the drug should be infused. It is also important to for aphysician to be able to monitor the position of the infusion needle withrespect to the wall of the organ. In the case of an organ, such as theheart, in which the walls are in constant motion, the activity ofpositioning and monitoring the position of the distal tip of thecatheter, or infusion needle, becomes especially difficult.

[0004] U.S. Pat. No. 3,598,119 discloses a medical device for injectingdrugs in which the injection needle is guided through an inner lumen ofa catheter for insertion of the needle under skin tissue. A bladder atthe distal end of the catheter may be inflated through another lumen forholding the point of the needle point in a fixed position beneath theskin.

[0005] U.S. Pat. No. 4,578,061 discloses a catheter for injecting aliquid into a vein, or artery, through an injection needle which islongitudinally movable beyond the distal end of the catheter. A dualchamber system is utilized within the catheter tip to provide formovement of a plunger to extend the injection needle and also to allowfor a plunger to be used to apply a predetermined dose of medicationthrough the injection needle.

[0006] U.S. Pat. No. 4,578,061 discloses an injection catheter having alongitudinal movable needle which may be moved through a lumen in orderto extend out of the side wall of the catheter for injecting a liquidinto a blood vessel. The needle is normally retracted into the device sothat the needle will not penetrate tissue as the device is moved througha body duct. Thereafter, the needle is moved out of the side of thecatheter into a vessel wall in order to infuse a liquid into the wall ofa vessel.

[0007] U.S. Pat. No. 5,244,460 is directed toward a method for improvingblood flow to the heart. More particularly this patent is directedtoward a medical procedure for improving the growth of cardiac bloodvessels by inserting a catheter into a coronary artery and injectinginto the heart a blood vessel growth promoting peptide through aninjection port of the catheter.

[0008] U.S. Pat. No. 5,419,777 is directed toward a catheter forinjection of a fluid into body cavities such as coronary vessels andarteries. This patent, as is the case with the '061 patent, illustratesthe use of an injection needle which protrudes laterally through theside walls of the distal tip of the catheter. In the case of druginjections to be made into coronary vessels and arteries, it is verydesirable to have the needles extend out of the side walls of thecatheter and at an acute angle to the walls of the vessel in order topenetrate the walls of the vessel for injection of the agent.

[0009] U.S. Pat. No. 5,431,168, assigned to the same assignee as thepresent patent application, is directed toward a steerable catheterwhich includes a puller wire for controlling the distal end of thecatheter from a control handle which is mounted on the proximal end ofthe catheter.

[0010] Copending U.S. patent application Ser. No. 09/019,453, entitled“Intracardiac Drug Delivery,” assigned to an affiliated company of theassignee of this application, discloses an injection catheter system forinfusing a diagnostic or therapeutic agent into the wall of an organwhich includes an electromagnetic sensor disposed within the distal tipof the catheter for providing very precise location information for thedistal tip of the catheter. The subject matter of this copending patentapplication is incorporated by reference into the subject patentapplication.

[0011] Copending U.S. patent application Ser. No. 09/280,202 disclosesan injection catheter where extension of the injection needle isdetermined by the amount of movement that is allowed in the injectionhandle. The injection handle is adjustable, permitting the physician toadjust the needle extension to the desired length. Although this designhas several advantages, it can cause the needle to buckle inside thecatheter due to frictional force between the needle and the housing inwhich the needle is mounted, which can result in unpredictable needleextension.

SUMMARY OF THE INVENTION

[0012] The present invention is directed to a catheter for infusingtherapeutic or diagnostic agents into the tissue of organs having asystem for predicable extension of the infusion needle, thereby reducingthe variability that can occur when the extent of the needle extensionis controlled by the needle control handle.

[0013] In one embodiment, the invention is directed to a cathetercomprising a catheter body comprising a flexible tubing having proximaland distal ends and at least one lumen therethrough. The catheterfurther includes a tip section comprising a flexible tubing havingproximal and distal ends, with the proximal end of the tip sectionmounted at the distal end of the catheter body. The tip section has aneedle passage extending therethough. The needle passage has a proximalregion having a proximal diameter and a distal region having a distaldiameter less than the proximal diameter. A needle control handle isprovided at the proximal end of the catheter body. An injection needleextends through the tip section, catheter body, and needle controlhandle and has a proximal end attached to the needle control handle anda distal end within the needle passage. The injection needle islongitudinally slidable so that its distal end can extend beyond thedistal end of the tip section upon suitable manipulation of the needlecontrol handle. A needle stop is mounted on a portion of the injectionneedle that is positioned within the proximal region of the needlepassage. The needle stop has a distal end that is sized to preventpassage of the portion of the injection needle on which the needle stopis mounted from passing into the distal region of the needle passage.The needle stop limits the distance that the injection needle can beextended beyond the distal end of the tip section.

[0014] In another embodiment, the invention is directed to a cathetercomprising a catheter body comprising a flexible tubing having proximaland distal ends and at least one needle passage extending therethrough.The needle passage has a proximal region having a proximal diameter anda distal region having a distal diameter less than the proximaldiameter. An injection needle extends through the catheter body and hasa distal end within the needle passage. The injection needle islongitudinally slidable so that its distal end can extend beyond thedistal end of the catheter. A needle stop is mounted on a portion of theinjection needle that is positioned within the proximal region of theneedle passage. The needle stop has a distal end that is sized toprevent passage of the portion of the injection needle on which theneedle stop is mounted from passing into the distal region of the needlepassage. The needle stop limits the distance that the injection needlecan be extended beyond the distal end of the catheter body.

DESCRIPTION OF THE DRAWINGS

[0015] These and other features and advantages of the present inventionwill be better understood by reference to the following detaileddescription when considered in conjunction with the accompanyingdrawings wherein:

[0016]FIG. 1 is a side plan view of one embodiment of the catheter ofthe present invention.

[0017]FIG. 2a is a side cross-sectional view of the needle controlhandle where the needle is in a retracted position.

[0018]FIG. 2b is a side cross-sectional view of the needle controlhandle where the needle is in an extended position.

[0019]FIG. 3 is a side cross-sectional view of a tip section accordingto the invention having three lumens, showing the injection needle and aneedle stop.

[0020]FIG. 3A is an enlarged view of the needle stop of FIG. 3.

[0021]FIG. 4 is a side cross-sectional view of the tip section of FIG. 3showing the position of the electromagnetic mapping sensor and thepuller wire.

[0022]FIG. 5 is a side cross-sectional view of the catheter body,including the junction between the catheter body and the section.

[0023]FIG. 6 is a transverse cross-sectional view of the tip section ofFIG. 3 along line 6-6 showing an embodiment having three lumens.

[0024]FIG. 7 is a transverse cross-sectional view of the catheter bodyalong line 7-7.

[0025]FIG. 8 is a side cross-sectional view of the catheter handle.

[0026]FIG. 9 is a schematic partial side cross-sectional view of a tipsection showing an alternative needle stop design in accordance with theinvention.

[0027]FIG. 10 is a schematic partial side cross-sectional view of a tipsection showing another alternative needle stop design in accordancewith the invention.

DETAILED DESCRIPTION

[0028] In a preferred embodiment of the invention, there is provided acatheter for use for injection of a therapeutic or diagnostic agent intothe heart. As shown in FIG. 1, catheter 10 comprises an elongatedcatheter body 12 having proximal and distal ends, a tip section 14 atthe distal end of the catheter body 12, a deflection control handle 16at the proximal end of the catheter body 12, and a needle control handle17 proximal the catheter body.

[0029] With reference to FIGS. 5 and 7, the catheter body 12 comprises asingle, central or axial lumen 18. The catheter body 12 is flexible,i.e., bendable, but substantially non-compressible along its length. Thecatheter body 12 may be of any suitable construction and made of anysuitable material. A presently preferred construction comprises an outerwall 22 made of a polyurethane or nylon. The outer wall 22 comprises animbedded braided mesh of stainless steel or the like to increasetorsional stiffness of the catheter body 12 so that, when the controlhandle 16 is rotated, the tip section of the catheter 10 will rotate ina corresponding manner.

[0030] The outer diameter of the catheter body 12 is not critical, butis preferably no more than about 8 French. Likewise the thickness of theouter wall 22 is not critical. The inner surface of the outer wall 22 islined with a stiffening tube 20, which can be made of any suitablematerial, preferably polyimide. The stiffening tube, along with thebraided outer wall 22, provides improved torsional stability while atthe same time minimizing the wall thickness of the catheter, thusmaximizing the diameter of the single lumen. The outer diameter of thestiffening tube 20 is about the same as or slightly smaller than theinner diameter of the outer wall 22. Polyimide tubing is presentlypreferred because it may be very thin walled while still providing verygood stiffness. This maximizes the diameter of the central lumen 18without sacrificing strength and stiffness. Polyimide material istypically not used for stiffening tubes because of its tendency to kinkwhen bent. However, it has been found that, in combination with an outerwall 22 of polyurethane, nylon or other similar material, particularlyhaving a stainless steel braided mesh, the tendency for the polyimidestiffening tube 20 to kink when bent is essentially eliminated withrespect to the applications for which the catheter is used. If desired,the stiffening tube 20 can be eliminated.

[0031] As shown in FIGS. 3, 4 and 6, the tip section 14 comprises ashort section of tubing 19 having three lumens 30, 32 and 34. The tubing19 is made of a suitable non-toxic material which is preferably moreflexible than the catheter body 12. A presently preferred material forthe tubing 19 is braided polyurethane, i.e., polyurethane with anembedded mesh of braided stainless steel or the like. The outer diameterof the tip section 14, like that of the catheter body 12, is preferablyno greater than about 8 French. The size of the lumens is not critical.In a particularly preferred embodiment, the tip section has an outerdiameter of about 7 French (0.092 inch) and the first lumen 30 andsecond lumen 32 are generally about the same size, having a diameter ofabout 0.022 inch, with the third lumen 34 having a slightly largerdiameter of about 0.036 inch.

[0032] If desired, the flexible tubing 19 of the tip section 14 can beeliminated, and the catheter body 12 can be provided with a singlelumen, as described, or multiple lumens, as desired.

[0033] A preferred means for attaching the catheter body 12 to the tipsection 14 is illustrated in FIG. 5. The proximal end of the tip section14 comprises an inner counter bore 24 that receives the outer surface ofthe polyimide stiffener 20. The tip section 14 and catheter body 12 areattached by glue or the like.

[0034] The stiffening tube 20 is held in place relative to the outerwall 22 at the proximal end of the catheter body 12. In preferredconstruction of the catheter body 12, a force is applied to the proximalend of the stiffening tube 20 which causes the distal end of thestiffening tube 20 to firmly push against the counter bore 24. Whileunder compression, a first glue joint is made between the stiffeningtube 20 and the outer wall 22 by a fast drying glue, e.g. Super Glue®.Thereafter a second glue joint is formed between the proximal ends ofthe stiffening tube 20 and outer wall 22 using a slower drying butstronger glue, e.g., polyurethane. Any other suitable method ofattaching the catheter body 12 to the tip section 14 can be used.

[0035] Extending through the single lumen 18 of the catheter body 12 arelead wires 40, an injection needle 46, a sensor cable 74, and acompression coil 44 through which a puller wire 42 extends. A singlelumen 18 catheter body is preferred over a multi-lumen body because ithas been found that the single lumen 18 body permits better tip controlwhen rotating the catheter 10. The single lumen 18 permits the leadwires 40, the injection needle 46, the sensor cable 74, and the pullerwire 42 surrounded by the compression coil 44 to float freely within thecatheter body. If such wires and cables were restricted within multiplelumens, they tend to build up energy when the handle 16 is rotated,resulting in the catheter body 12 having a tendency to rotate back if,for example, the handle is released, or if bent around a curve, to flipover, either for which are undesirable performance characteristics.

[0036] With reference to FIGS. 3 and 4, mounted at the distal end of thetip section 14 is a tip electrode 36. Preferably the tip electrode 36has a diameter about the same as the outer diameter of the tubing 19.The tip electrode 36 is connected to the tubing 19 by means of a plastichousing 21, preferably made of polyetheretherketone (PEEK). The proximalend of the tip electrode 36 is notched circumferentially and fits insidethe distal end of the plastic housing 21 and is bonded to the housing 21by polyurethane glue or the like. The proximal end of the plastichousing 21 is bonded with polyurethane glue or the like to the distalend of the tubing 19 of the tip section 14. Alternatively, the tipelectrode 36 can be mounted directly to the distal end of the flexibletubing 19 of the tip section 14.

[0037] Mounted on the distal end of the plastic housing 21 is a ringelectrode 38. The ring electrode 38 is slid over the plastic housing 21and fixed in place by glue or the like. If desired, additional ringelectrodes may be used and can be positioned over the plastic housing 21or over the flexible tubing 19 of the tip section 14.

[0038] The tip electrode 36 and ring electrode 38 are each connected toa separate lead wire 40. The lead wires 40 extend through the thirdlumen 34 of tip section 14, the catheter body 12, and the control handle16, and terminate at their proximal end in an input jack (not shown)that may be plugged into an appropriate monitor (not shown). If desired,the portion of the lead wires 40 extending through the catheter body 12,control handle 16 and proximal end of the tip section 14 may be enclosedor bundled within a protective tube or sheath.

[0039] The lead wires 40 are attached to the tip electrode 36 and ringelectrode 38 by any conventional technique. Connection of lead wire 40to the tip electrode 36 is preferably accomplished by weld 43, as shownin FIG. 4.

[0040] A puller wire 42 is provided for deflection of the tip section14. The puller wire 42 is anchored at its proximal end to the controlhandle 16 and anchored at its distal end to the tip section 14. Thepuller wire 42 is made of any suitable metal, such as stainless steel orNitinol, and is preferably coated with Teflon® or the like. The coatingimparts lubricity to the puller wire 42. The puller wire 42 preferablyhas a diameter ranging from about 0.006 to about 0.010 inches.

[0041] As discussed above, a compression coil 44 is provided insurrounding relation to a portion of the puller wire 42. The compressioncoil 44 extends from the proximal end of the catheter body 12 to theproximal end of the tip section 14. The compression coil 44 is made ofany suitable metal, preferably stainless steel. The compression coil 44is tightly wound on itself to provide flexibility, i.e., bending, but toresist compression. The inner diameter of the compression coil 44 ispreferably slightly larger than the diameter of the puller wire 42. Forexample, when the puller wire 42 has a diameter of about 0.007 inches,the compression coil 44 preferably has an inner diameter of about 0.008inches. The Teflon® coating on the puller wire 42 allows it to slidefreely within the compression coil 44. Along its length, the outersurface of the compression coil 44 is covered by a flexible,non-conductive sheath 26 to prevent contact between the compression coil44 and any of the lead wires 40, injection needle 46 or sensor cable 74.A non-conductive sheath 26 made of polyimide tubing is presentlypreferred.

[0042] The compression coil 44 is anchored at its proximal end to theproximal end of the stiffening tube 20 in the catheter body 12 by glueto form a glue joint 50 and at its distal end to the tip section 14 inthe second lumen 32, also forming a glue joint 50. The glue may beapplied by means of a syringe or the like through a hole made betweenthe outer surface of the catheter body 12 and the single lumen.

[0043] The puller wire 42 extends into the second lumen 32 of the tipsection 14. The distal end of the puller wire 42 is anchored to the tipelectrode 36 or to the side of the catheter tip section 14. Withreference to FIGS. 4 and 5, within the tip section 14, and distal to theglue joint 50, the turns of the compression coil are expandedlongitudinally. Such expanded turns 49 are both bendable andcompressible and preferably extend for a length of about 0.5 inch. Thepuller wire 42 extends through the expanded turns 49 then into aplastic, preferably Teflon®, sheath 81, which prevents the puller 42from cutting into the wall of the tip section 14 when the section 14 isdeflected.

[0044] An injection needle 46 is provided, which extends from the needlecontrol handle through the catheter body 12, through the first lumen 30of the tip section 14 and through a passage 51 in the tip electrode 36.As illustrated in FIG. 3, the injection needle 46 is preferably formedwith a beveled edge at the distal tip of the needle.

[0045] In one embodiment, the injection needle 46 is formed of Nitinol.Alternatively, the injection needle 46 is formed of plastic, or aportion of the needle is formed of plastic and another portion of theneedle is formed of metal, such as Nitinol, as described in more detailin copending U.S. Patent Application entitled “Catheter with InjectionNeedle,” to Dean Ponzi, filed on even date herewith, the entiredisclosure of which is incorporated herein by reference. If desired, theinjection needle 46 can be provided with one or more fluid openingsalong its length to permit fluid flow out the side of the needle as wellas out the distal end, as also described in copending U.S. PatentApplication entitled “Catheter with Injection Needle.”

[0046] The needle 46 is coaxially mounted within a protective tube 47,preferably made of polyimide, which serves to prevent the needle frombuckling and also serves to electrically insulate the needle from thedistal electrode 36. The protective tube 47 additionally serves toprovide a fluid-tight seal surrounding the distal end of the injectionneedle 46. FIG. 3 depicts the injection needle 46 extending beyond thedistal end of the tip electrode 36, as it would be positioned in orderto infuse diagnostic or therapeutic fluid into the human heart. Thedistal end of the injection needle 46 is withdrawn into the tipelectrode 36 during the period of time that the catheter is insertedthrough the vasculature of the body and also during the period of timein which the catheter is removed from the body to avoid injury.Alternatively, the tip section 14 can be provided without a tipelectrode 36, in which case the distal end of the injection needle 46could be retracted into the first lumen 30 of the tip section 14. Ineither embodiment, the injection needle 46 is extendable and retractablebeyond the distal end of the catheter.

[0047] In the depicted embodiment, the inner region of the protectivetube 47 serves as a needle passage. The needle passage has a proximalregion 52 with a proximal diameter and a distal region 55 with a distaldiameter that is less than the proximal diameter. The distal diameter isapproximately equal to the outer diameter of the injection needle 46 toprovide a fluid-tight seal, as described above. This design creates astep 48 at the distal end of the proximal region 52. A needle stop 59 ismounted on a portion of the injection needle 46 that is positionedwithin the proximal region 52 of the needle passage. The needle stop 59is sized to prevent passage of the portion of the injection needle onwhich the needle stop is mounted from passing into the distal region 55of the needle passage. In the embodiment depicted in FIG. 3, the needlestop 59 is in the form of a collar that is mounted in surroundingrelation to the injection needle 46. The collar extends only a shortlength along the needle, e.g., a distance ranging from about 0.01 inchto about 0.75 inch.

[0048] This design limits the distance that the injection needle 46 canextend beyond the distal end of the tip section 14. As described in moredetail below, needle extension and retraction is accomplished with theneedle control handle. When the injection needle 46 is moved distallyusing the needle control handle, it pushes the needle stop 59 distallyinto the step 48 at the distal end of the proximal region 52. Theinteraction between the needle stop 59 and the step 48 prevents furtherdistal movement of the injection needle 46, thereby limiting the extentto which the needle can extend beyond the distal end of the tip section14. This design ensures that the needle always extends out of the tipsection 14 the same distance, regardless of whether the tip section isstraight or deflected.

[0049]FIG. 9 depicts an alternative design for the needle passage andneedle stop. In this embodiment, a lumen 61 in the tubing 19 of the tipsection 14 serves as the proximal region 52 of the needle passage. As inthe embodiment of FIG. 3, a passage 51 is provided in the tip electrode36. Within the tip electrode 36, the needle 46 is coaxially mountedwithin a protective tube 47, although the protective tube does notextend into the lumen 61. The inner region of the protective tube 47serves as the distal region 55 of the needle passage. The inner diameterof the lumen 61 is thus larger than the inner diameter of the protective47, thus creating a step 48 at the distal end of the lumen. An elongatedtube 63, preferably having a length of at least about 2 inches, iscoaxially mounted around a portion of the injection needle 46 that is inthe proximal region 52. The elongated tube 63 can be made of anysuitable material, such as plastic or Nitinol. The elongated tube 63 hasan diameter greater than the inner diameter of the protective tube 47,and thus serves as a needle stop in a manner similar to the collardescribed above.

[0050] The needle stop 59 need not be coaxially mounted on the injectionneedle 46. For example, the needle stop could be in the form of arectangular tab that is mounted on only a portion of the circumferenceof the injection needle 46. Any other suitable design can be providedfor the needle stop 59, so long as the needle stop is of a size andshape so that it cannot pass into the distal region 55 of the needlepassage.

[0051] In another alternative design, as shown in FIG. 10, the needlestop 59 is integral with the injection needle 46. In this embodiment,the injection needle 46 is formed of two pieces of tubing, a proximaltubing 65 and a distal tubing 67, each of which can be made of anysuitable material as described above, such as metal or plastic. Theproximal end of the distal tubing 67 is bonded or otherwise attached tothe distal end of the proximal tubing 65. Preferably the proximal end ofthe distal tubing 67 is inserted into the distal end of the proximaltubing 65 and attached by polyurethane glue or the like. The proximaltubing 65 has an outer diameter greater than the outer diameter of thedistal tubing 67 and greater than the inner diameter of the distalregion 55 of the needle passage. The proximal tubing thus acts as theneedle stop 59.

[0052] The needle passage can be formed by any suitable combination ofelements in the tip section so long as it has a proximal region 52 witha proximal diameter and a distal region 55 with a distal diameter thatis less than the proximal diameter. Thus, the needle passage can beformed from a tubing that is separate from the tip section 14, as shown,for example, in FIGS. 3 and 10, discussed above. Alternatively, theneedle passage can be formed directly in the tip section 14 and tipelectrode 36, or directly in the tip section only if no tip electrode isprovided. In another alternative, a combination of these approaches canbe provided, for example, as shown in FIG. 9 discussed above.

[0053] Additionally, an electromagnetic sensor 72 is contained withinthe distal end of the tip section 14. The electromagnetic sensor 72 isconnected to an electromagnetic sensor cable 74, which extends throughthe third lumen 34 of the tip section 14 through the catheter body 12into the control handle 16. The electromagnetic sensor cable 74comprises multiple wires encased within a plastic sheath. In the controlhandle 16, the wires of the sensor-cable 74 are connected to a circuitboard 64. The circuit board 64 amplifies the signal received from theelectromagnetic sensor and transmits it to a computer in a formunderstandable by the computer. Also, because the catheter is designedfor single use only, the circuit board contains an EPROM chip whichshuts down the circuit board after the catheter has been used. Thisprevents the catheter, or at least the electromagnetic sensor, frombeing used twice. Suitable electromagnetic sensors for use in connectionwith the present invention are described, for example, in U.S. Pat. No.4,391,199 and U.S. patent application Ser. No. 09/160,063, entitled“Miniaturized Position Sensor,” the disclosures of which areincorporated herein by reference. A preferred electromagnetic mappingsensor 72 is manufactured by Biosense Webster, Inc. and marketed underthe trade designation NOGA. To use the electromagnetic sensor 72, thepatient is placed in a magnetic field generated, for example, bysituating under the patient a pad containing coils for generating amagnetic field. A reference electromagnetic sensor is fixed relative tothe patient, e.g., taped to the patient's back, and the injectioncatheter containing a second electromagnetic sensor is advanced into thepatient's heart. Each sensor comprises three small coils which in themagnetic field generate weak electrical signals indicative of theirposition in the magnetic field. Signals generated by both the fixedreference sensor and the second sensor in the heart are amplified andtransmitted to a computer which analyzes the signals and then displaysthe signals on a monitor. By this method, the precise location of thesensor in the catheter relative to the reference sensor can beascertained and visually displayed. The sensor can also detectdisplacement of the catheter that is caused by contraction of the heartmuscle.

[0054] Using this technology, the physician can visually map a heartchamber. This mapping is done by advancing the catheter tip into a heartchamber until contact is made with the heart wall. This position isrecorded and saved. The catheter tip is then moved to another positionin contact with the heart wall and again the position is recorded andsaved.

[0055] The electromagnetic mapping sensor 72 can be used alone or morepreferably in combination with the tip electrode 36 and ring electrode38. By combining the electromagnetic sensor 72 and electrodes 36 and 38,a physician can simultaneously map the contours or shape of the heartchamber, the electrical activity of the heart, and the extent ofdisplacement of the catheter and hence identify the presence andlocation of the ischemic tissue. Specifically, the electromagneticmapping sensor 72 is used to monitor the precise location of the tipelectrode in the heart and the extent of catheter displacement. The tipelectrode 36 and ring electrode 38 are used to monitor the strength ofthe electrical signals at that location. Healthy heart tissue isidentified by strong electrical signals in combination with strongdisplacement. Dead or diseased heart tissue is identified by weakelectrical signals in combination with dysfunctional displacement, i.e.,displacement in a direction opposite that of healthy tissue. Ischemic,or hibernating or stunned, heart tissue is identified by strongelectrical signals in combination with impaired displacement. Hence, thecombination of the electromagnetic mapping sensor 72 and tip and ringelectrodes 36 and 38 is used as a diagnostic catheter to determinewhether and where to infuse a drug into the wall of the heart. Once thepresence and location of ischemic tissue has been identified, the tipsection 14 of the catheter can be deflected so that the injection needle46 is generally normal, i.e., at a right angle, to the ischemic tissue,and the injection needle may then be extended out of the distal end ofthe tip electrode 36 and into the wall of the heart.

[0056] It is understood that, while it is preferred to include bothelectrophysiology electrodes and an electromagnetic sensor in thecatheter tip, it is not necessary to include both. For example, aninjection catheter having an electromagnetic sensor but noelectrophysiology electrodes may be used in combination with a separatemapping catheter system. A preferred mapping system includes a cathetercomprising multiple electrodes and an electromagnetic sensor, such asthe NOGA-STAR catheter marketed by Biosense Webster, Inc., and means formonitoring and displaying the signals received from the electrodes andelectromagnetic sensor, such as the Biosense-NOGA system, also marketedby Biosense Webster, Inc.

[0057] The electrode lead wires 40 and electromagnetic sensor cable 74must be allowed some longitudinal movement within the catheter body sothat they do not break when the tip section 14 is deflected. To providefor such lengthwise movement, there is provided a tunnel through theglue joint 50, which fixes the proximal end of the compression coil 44inside the catheter body 12. The tunnel is formed by a transfer tube 27,preferably made of a short segment of polyimide tubing. Preferably thetransfer tube is approximately 60 mm long and has an outer diameter ofabout 0.021 inch and an inner diameter of about 0.019 inch.

[0058] Longitudinal movement of the puller wire 42 relative to thecatheter body 12, which results in deflection of the tip section 12, isaccomplished by suitable manipulation of the control handle 16. As shownin FIG. 8, the distal end of the control handle 16 comprises a piston 54with a thumb control 56 for manipulating the puller wire 42. Theproximal end of the catheter body 12 is connected to the piston 54 bymeans of a shrink sleeve 28.

[0059] The injection needle 46 within the protective tube 47, the pullerwire 42, the lead wires 40 and the electromagnetic sensor cable 74extend through the piston 54. The puller wire 42 is anchored to ananchor pin 57 located proximal to the piston 54. The lead wires 40 andelectromagnetic sensor cable 74 extend through a first tunnel 58,located near the side of the control handle 16. The electromagneticsensor cable 74 connects to the circuit board 64 in the proximal end ofthe control handle. Wires 73 connect the circuit board 64 to a computerand imaging monitor (not shown).

[0060] The injection needle 46 and protective tube 47 extend through aguide tube 66, preferably made of polyurethane, and are affordedlongitudinal movement therein. The guide tube 66 is anchored to thepiston 54, preferably by glue at glue joint 53. This design allows theneedle 46 and protective tube 47 longitudinal movement within thecontrol handle 16 so that the needle 46 does not break when the piston54 is adjusted to manipulate the puller wire 42. Within the piston 54,the electromagnetic sensor cable 74 and lead wires 40 are situatedwithin a transfer tube 27 a, and the puller wire 42 is situated withinanother transfer tube 27 b to allow longitudinal movement of the wiresand cable near the glue joint 53.

[0061] The injection needle 46, protective tube 47 and guide tube 66extend through a second tunnel 60 situated near the side of the controlhandle 16 opposite the anchor pin 36. To avoid undesirable bending ofthe injection needle 46, a space 62 is provided between the proximal endof the piston 54 and the distal end of the second tunnel 60. Preferablythe space 62 has a length of at least 0.50 inch and more preferablyabout from about 0.60 inch to about 0.90 inch.

[0062] In the proximal end of the control handle 16, the injectionneedle 46, protective tube 47 and polyurethane guide tube 66 extendthrough a second larger plastic guide tube 68, preferably made ofTeflon®, which affords the guide tube 66, injection needle 46, andprotective tube 47 longitudinal slidable movement. The second guide tube68 is anchored to the inside of the control handle 16 by glue or thelike and extends proximally beyond the control handle 16. The secondguide tube 68 protects the injection needle 46 both from contact withthe circuit board 64 and from any sharp bends as the guide tube 66,needle 46, and protective tube 47 emerge from the control handle 16.

[0063] Extension and retraction of the injection needle 46 out thedistal end of the tip electrode 36 is accomplished by the needle controlhandle 17. As illustrated in FIGS. 2a and 2 b, the needle control handle17 comprises a generally cylindrical outer body 80 having proximal anddistal ends, a piston chamber 82 extending a part of the waytherethrough, and a needle passage 83 extending a part of the waytherethrough. The piston chamber 82 extends from the proximal end of thehandle part way into the body 80, but does not extend out the distal endof the body. The needle passage 83, which has a diameter less than thatof the piston chamber 82, extends from the proximal end of the pistonchamber to the proximal end of the outer body 80.

[0064] A piston 84, having proximal and distal ends, is slidably mountedwithin the piston chamber 82. A Luer connector 86 is mounted in thedistal end of the outer body. The piston 84 has an axial passage 85through which the injection needle 46 extends, as described in moredetail below. A compression spring 88 is mounted within the pistonchamber 82 between the distal end of the piston 84 and the outer body80.

[0065] The proximal end of the injection needle 46 is mounted to theLuer connector 86 by means of a first rigid tube 90, preferably made ofstainless steel, which has a proximal end fitted into the Luerconnector. This arrangement fixedly attaches the injection needle 46 tothe piston 84 so that it moves longitudinally with the piston. The firstrigid tube 90 is also fixedly attached to the piston 84 and moveslongitudinally with the piston. The injection needle 46 and first rigidtube 90 extend through the axial passage 85 of the piston 84. Within theaxial passage 85, a second rigid tube 91, preferably made of stainlesssteel, has a proximal end mounted coaxially within the distal end of thefirst rigid tube 90. The proximal end of the second rigid tube 91 ismounted within the protective tube 47, which has its proximal end insidethe axial passage 85, and the distal end of the second rigid tube isattached, directly or indirectly, to the outer body 80. The guide tube66, through which the protective tube 47 and injection needle 46 extend,as discussed above, is fixedly attached to the outer body 80 by means ofa shrink sleeve 92, as is generally known in the art.

[0066] In use, force is applied to the piston 84 to cause distalmovement of the piston relative to the outer body 21, which compressesthe compression spring 88. This movement causes the injection needle 46to correspondingly move distally relative to the outer body, guide tube66, protective tube 47 and catheter body 12, so that the distal end ofthe injection needle extends outside the distal end of the tip electrode36. When the force is removed from the piston, the compression spring 88pushes the piston 84 proximally to its original position, thus causingthe distal end of the injection needle 46 to retract back into the tipelectrode 36. Upon distal movement of the piston 84, the first rigidtube 91 moves distally over the second rigid tube 91 to prevent theinjection needle 46 from buckling within the axial passage 85.

[0067] The piston 84 further comprises a longitudinal slot 100 extendingalong a portion of its outer edge. A set screw 102 extends through theouter body 80 and into the longitudinal slot 100. This design limits thedistance that the piston can be slid proximally out of the pistonchamber 82. When the distal end of the injection needle 46 is in theretracted position, preferably the set screw 102 is at or near thedistal end of the longitudinal slot 100.

[0068] The proximal end of the piston 84 has a threaded outer surface104. A circular thumb control 106 is mounted on the proximal end of thepiston. The thumb control 106 has a threaded inner surface 108 thatinteracts with the threaded outer surface 104 of the piston. The thumbcontrol 106 acts as a stop, limiting the distance that the piston 84 canbe pushed into the piston chamber 82, and thus the distance that theinjection needle 46 can be extended out the distal end of the catheter.The threaded surfaces of the thumb control 106 and piston 84 allow thethumb control to be moved closer or farther from the proximal end of theouter body 80 so that the extension distance of the injection needle canbe controlled by the physician. A tension screw 110 is provided in thethumb control 106 to control the tension between the thumb control andpiston 84. As would be recognized by one skilled in the art, the thumbcontrol 106 can be replaced by any other mechanism that can act as astop for limiting the distance that the piston 84 extends into thepiston chamber 82, and it is not necessary, although it is preferred,that the stop be adjustable relative to the piston.

[0069] In another preferred embodiment constructed in accordance withthe present invention, two or more puller wires (not shown) are providedto enhance the ability to manipulate the tip section. In such anembodiment, a second puller wire and a surrounding second compressioncoil extend through the catheter body and into separate off-axis lumensin the tip section. The lumens of the tip section receiving the pullerwires may be in adjacent quadrants. The first puller wire is preferablyanchored proximal to the anchor location of the second puller wire. Thesecond puller wire may be anchored to the tip electrode or may beanchored to the wall of the tip section adjacent the distal end of tipsection.

[0070] The distance between the distal end of the compression coils andthe anchor sites of each puller wire in the tip section determines thecurvature of the tip section 14 in the direction of the puller wires.For example, an arrangement wherein the two puller wires are anchored atdifferent distances from the distal ends of the compression coils allowsa long reach curve in a first plane and a short reach curve in a plane90° from the first, i.e., a first curve in one plane generally along theaxis of the tip section before it is deflected and a second curve distalto the first curve in a plane transverse, and preferably normal to thefirst plane. The high torque characteristic of the catheter tip section12 reduces the tendency for the deflection in one direction to deformthe deflection in the other direction. Suitable deflection controlhandles for use with such a catheter are described in U.S. patentapplication Ser. Nos. 08/924,611, filed Sep. 5, 1997, entitled“Omni-Directional Steerable Catheter”, 09/130,359, filed Aug. 7, 1998,entitled “Bi-Directional Control Handle for Steerable Catheter”, and09/143,426, filed Aug. 28, 1998, entitled “Bidirectional SteerableCatheter with Bidirectional Control Handle”, and U.S. Patent Applicationentitled “Single Gear Drive Bidirectional Control Handle for SteerableCatheter” to Tim Bumbalough, et al., filed Apr. 10, 2000, thedisclosures of which are incorporated herein by reference.

[0071] As an alternative to the above described embodiment, the pullerwires (not shown) may extend into diametrically opposed off-axis lumensin the tip section. In such an embodiment, each of the puller wires maybe anchored at the same location along the length of the tip section, inwhich case the curvatures of the tip section in opposing directions arethe same and the tip section can be made to deflect in either directionwithout rotation of the catheter body.

[0072] The preceding description has been presented with reference topresently preferred embodiments of the invention. Workers skilled in theart and technology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningful departing from the principal, spirit and scope ofthis invention.

[0073] Accordingly, the foregoing description should not be read aspertaining only to the precise structures described and illustrated inthe accompanying drawings, but rather should be read consistent with andas support to the following claims which are to have their fullest andfair scope.

What is claimed is:
 1. A steerable cardiac drug injection cathetercomprising: a catheter body having an outer wall, proximal and distalends, and at least one lumen extending therethrough; a control handlefixedly attached to the proximal end of the catheter body; a tip sectioncomprising flexible tubing having proximal and distal ends and at leastone lumen extending therethrough, the proximal end of the tip sectionbeing fixedly attached to the distal end of the catheter body; aninjection needle which is straight and smooth over its entire lengthextends through the lumen in the catheter body and the lumen in the tipsection and extends in fluid tight engagement through the lumen of thetip electrode, said needle being slidable from a first position in whichthe needle is withdrawn into the tip electrode to a second position inwhich the needle extends out of the distal face of the tip electrode; aneedle control knob mounted on the control handle and connected to theproximal end of the injection needle for sliding the injection needlefrom the first position to the second position; and, a deflectioncontrol mounted on the control handle for deflecting the catheter uponmanipulation of the deflection control, said deflection control takesthe form of a control knob longitudinally movable with respect to thecontrol handle for deflecting the tip section of the injection catheter.2. An injection catheter according to claim 1, further comprising anelectromagnetic mapping sensor disposed in the tip section for producingelectrical signals indicative of the position of the electromagneticmapping sensor relative to the position of a reference electrode sensor.3. An injection catheter according to claim 2, further comprising asensor cable electrically attached to the electromagnetic mapping sensorand extending through the lumen in the tip section, through the lumen inthe catheter body and into the control handle, and the sensor cable iselectrically attached to a circuit board situated within the controlhandle.
 4. An injection catheter according to claim 3, wherein thecontrol handle comprises a first member fixedly attached to the proximalend of the catheter body and a second member that is movable relative tothe first member.
 5. An injection catheter according to claim 4, whereinthe deflection control comprises a puller wire having a proximal end anda distal end, the puller wire extending from the control handle, throughthe lumen in the catheter body and is fixedly secured within the tipsection, and the proximal end of the puller wire is fixedly secured tothe second member of the control handle, whereby manipulation of thefirst member of the control handle relative to the second member of thecontrol handle moves the puller wire relative to the catheter bodyresulting in deflection of the tip section.
 6. An injection catheter asdefined in claim 5, wherein the first member of the control handle ismovable from a first position to a second position relative to thesecond member of the control handle, and the puller wire is fixedlysecured to the second member of the control handle such that when thesecond member of the control handle is moved from the first position tothe second position the puller wire causes the tip section of thecatheter to be deflected from a normally straight position to adeflected position.
 7. An injection catheter according to claim 6,wherein the deflection control further comprises a compression coilsituated in the catheter body in surrounding relation to the puller wireand extending into the lumen in the tip section.
 8. An injectioncatheter according to claim 7, wherein the compression coil is anchoredto the catheter at the proximal end of the catheter body and at theproximal end of the tip section.
 9. An injection catheter as defined inclaim 1, wherein the outer diameter of the injection needle issubstantially the same as the diameter of the lumen through the tipsection to thereby prevent the flow of blood through the lumen of thetip section and the lumen of the catheter body.
 10. An injectioncatheter as defined in claim 9, wherein the needle is formed of an alloycomprised of nickel and titanium.
 11. An injection catheter as definedin claim 1, including a sleeve member having a lumen therethrough, saidsleeve member is disposed within the lumen of the tip electrode; theneedle slidably engages the lumen in the sleeve member; and, the needleis formed of an alloy comprising nickel and titanium.
 12. A steerablecardiac drug injection catheter comprising: A catheter body having anouter wall, proximal and distal ends, and at least one lumen extendingtherethrough; a control handle fixedly attached to the proximal end ofthe catheter body; a tip section comprising flexible tubing havingproximal and distal ends and at least one lumen extending therethrough,the proximal end of the tip section being fixedly attached to the distalend of the catheter body; an injection needle which is straight andsmooth over its entire length extends through the lumen in the catheterbody and extending in fluid-tight engagement through the lumen in thetip section, said needle being slidable from a first position in whichthe needle is withdrawn into the tip section to a second position inwhich the needle extends out of the tip section; a slidable needlecontrol knob mounted on the control handle and connected to the proximalend of the injection needle for sliding the injection needle from thefirst position to the second position; and, a deflection control mountedon the control handle for deflecting the catheter upon manipulation ofthe deflection control, said deflection control takes the form of acontrol knob longitudinally movable with respect to the control handlefor deflecting the tip section of the injection catheter.
 13. Aninjection catheter as defined in claim 12, wherein the outer diameter ofthe needle is substantially the same as the diameter of the lumenthrough the tip section to thereby prevent the flow of blood through thelumen of the tip section and the lumen of the catheter body.
 14. AnInjection catheter as defined in claim 13, wherein the needle is formedof an alloy comprised of nickel and titanium.
 15. An injection catheteras defined in claim 13, including a sleeve member having a lumentherethrough, said sleeve member is disposed within the lumen of the tipsection; the needle slidably engages the lumen in the sleeve member;and, the needle is formed of an alloy comprising nickel and titanium.16. A catheter as defined in clam 12, further comprising anelectromagnetic mapping sensor in the tip section for producingelectrical signals indicative of the location of the electromagneticmapping sensor.
 17. A catheter as defined in claim 16, furthercomprising a sensor cable electrically attached to the electromagneticmapping sensor and extending through a lumen in the tip section, througha lumen in the catheter body and into the control handle, wherein thesensor cable is electrically attached to a circuit board situated withinthe control handle.